The invention relates to a process of producing an inner profile in a tube or hollow profile.
In this process, the tube or hollow profile, prior to being deformed, comprises a substantially uniform wall thickness and is placed into a suitable supporting sleeve and is deformed by pressing in a forming die—whose outer profile corresponds to the inner profile to be produced—starting from one tube end. The material displaced as a result of the production of the profile leads to a backward extrusion of the deformed tube or profile at the tube end inside the supporting sleeve.
When carrying out said prior art process, there exist limits regarding the profile height, i.e. the difference between the smallest cross-section and the greatest cross-section of the forming die in that, with an increasing degree of deformation, the profile filling becomes inadequate. The material no longer fully fills the tool contour of the forming die, which results in an unusable product. In addition, it is possible that, in the running-in region, the portion of the inner profile where the least change in shape occurs is subject to under-filling.